Chuck for tools

ABSTRACT

A chuck for tools comprises a main body in which an axial center hole and a plurality of slanting holes extending radially from the center hole are formed, a plurality of jaws each being slidably inserted in each slanting hole and formed, at its outer surface, with a male screw, a rotary member having a female screw in meshing engagement with the male screws and mounted in the main body so as to be permitted for only rotation, a first grip integrally connected to the main body, and a second grip securely connected to the rotary member to cooperate therewith.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a chuck for tools such as drills.

2. Description of the Prior Art

Conventionally, a typical example of this type of chuck for tools hasbeen known as disclosed in Japanese Patent Publication No. 55-25002(U.K.P. No. 1468639) and will be explained herein with reference to FIG.1 in the accompanying drawings.

This prior art chuck has a main body 1 and in the forward end portion ofthe main body 1, a center hole 4 is bored which extends axially in orderthat the shank of a tool T is received in the center hole 4. This centerhole 4 branches at equal angular intervals to a plurality of (typicallythree) slanting holes 5 which extend obliquely toward the rear of thechuck, and jaws 2 are slidably inserted in the slanting holes 5.

Each jaw 2 has, at its forward end, an inner surface 6 which extends inparallel with the axis line of the main body 1, and when the jaws 2 areadvanced forwardly (to the left in the illustration), they clamp thetool T as shown in FIG. 1. Threaded on the rearward outer surface ofeach jaw 2 is a male screw 7 which meshes with a female screw 8 of arotary member 3 rotatably received in an annular groove 9 formed in themain body 1. The rotary member 3 is formed, at its forward end, with abevel gear 10. The main body 1 has a radial blind hole 11.

With the chuck for tools constructed as above, in order to move the jaws2 within the main body 1, a tip end shape 12 of a handle 13 is insertedto the blind hole 11 to bring a bevel gear 14 of the handle 13 intomeshing engagement with the bevel gear 10 and the rotary member 3 isthen rotated by rotating the handle 13. This rotation of the rotarymember 3 cooperates with the screws 7 and 8 to move the jaws 2 along theslanting holes 5, so that the tool T may be clamped by the jaws 2 whenthey are advanced and released from the jaws 2 when they are retreated.

This prior art chuck for tools needs the separate handle 13, independentof the chuck per se, for the purpose of moving the jaws 2 and it isimpossible to move the jaws 2 without using the handle 13. If the handle13 is lost or can not be found at hand, one may try to clamp or releasethe tool T by rotating the rotary member 3, but the rotary member 3 mayonly be rotated together with the main body 3 and the trial may be donein vain, indicating a failure to accomplish the intended purpose.

SUMMARY OF THE INVENTION

An object of this invention is to eliminate the disadvantages of theprior art chuck for tools and to provide a chuck for tools which can beoperated by itself without resort to any tools independent of the chuckto move the jaws so as to clamp or release a tool.

According to the invention, to accomplish the above object, a chuck fortools comprises a main body in which an axial center hole and aplurality of slanting holes extending radially from the center hole areformed, a plurality of jaws each being slidably inserted in eachslanting hole and formed, at its outer surface, with a male screw, arotary member having a female screw in meshing engagement with the malescrews and mounted in the main body so as to be permitted for onlyrotation, a first grip integrally connected to the main body, and asecond grip securely connected to the rotary member to cooperatetherewith.

With the chuck for tools constructed above, the jaws can be advanced orretreated within the slanting holes in the main body with the aim ofclamping or releasing the tool by relatively rotating the first grip ofmain body gripped by one hand and the second grip of rotary membergripped by the other hand in one direction or in the direction reversethereto. This relative rotation causes the female screw of the rotarymember to rotate relative to the main body and the male screws, inmeshing engagement with the female screw, of the jaws axially slidablyinserted in the slanting holes in the main body act to cause the jaws toadvance or retreat.

As is clear from the above, the chuck for tools in accordance with theinvention does not require any operation tools independent of the chuck,such as the handle used conventionally, for the sake of moving the jaws,and the chuck per se can readily be operated by hand to clamp the toolsecurely or to release the tool.

Another object of this invention is to provide a chuck for tools inwhich the relative rotation between the first and second grips can beeffected by a relatively small force.

This second object can be accomplished by interposing bearing ballsbetween relatively rotatable opposing surfaces of the main body and therotary member. Thus, the bearing balls can considerably reduce frictionbetween the opposing surfaces to realize light rotation.

Still another object of this invention is to provide a chuck for toolsin which the tool once clamped by the jaws can automatically be clampedmore strongly by merely continuing rotating the second grip in the samedirection for clamping.

To accomplish this third object, the rotary member and the second gripare coupled together by means of a coupling member made of a resilentmaterial and when a reaction force of tool clamping force generated inthe course of the rotation of the second grip is transmitted to therotary member, the coupling member releases the rotary member fromcoupling to the second grip and the rotary member undergoing releasefrom coupling stops rotating and displaces rearwardly. A pusher membermaking surface contact to part of the first grip is interposed betweenthe first and second grips and when the rotation of the second gripcontinues during the displacement of the rotary member, the pushermember causes the rotary member to displace forwardly. Thus, upongeneration of the reaction force of tool clamping force, the rotation ofthe rotary member is stopped but a rearward pushing force is generatedto permit the pusher member to rotate together with the second grip.This rotation of the pusher member causes the pusher member to advanceforwardly and an advancing force is transmitted to the jaws through therotary member to cause the jaws to clamp the tool more strongly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinally section front view illustrating an typicalexample of prior art chuck for tools.

FIG. 2 is a section view, taken on the line 2--2 of FIG. 3 and viewed inthe direction of arrow, showing a chuck for tools according to a firstembodiment of the invention.

FIG. 3 is a left side view of the FIG. 2 embodiment.

FIG. 4 is a longitudinally sectional front view illustrating a chuck fortools according to a second embodiment of the invention.

FIG. 5 is a sectional view taken on the line 5--5 of FIG. 4 and viewedin the direction of arrow.

FIG. 6 is an enlarged sectional view illustrating essential part of thesecond embodiment placed in clamping condition.

FIG. 7 is a fragmentary sectional view taken on the line 7--7 of FIG. 6.

FIG. 8 is a sectional view, taken on the line 8--8 of FIG. 9 and viewedin the direction of arrow, showing a chuck for tools according to athird embodiment of the invention.

FIG. 9 is a left side view of the FIG. 8 embodiment.

FIG. 10 is an enlarged fragmentary view showing a portion surrounded byline 10 in FIG. 8.

FIG. 11 is a longitudinally sectional fragmentary view showing part of achuck for tools according to a fourth embodiment of the invention.

FIG. 12 is a similar view to FIG. 11 illustrating a chuck for toolsaccording to fifth embodiment of the invention.

FIG. 13 is a longitudinal sectional front view illustrating a chuck fortools according to a sixth embodiment of the invention.

FIG. 14 is a sectional view, taken on the line 14--14 of FIG. 13 andviewed in the direction of arrow, showing the second grip of the FIG. 13embodiment.

FIG. 15 is a longitudinal sectional front view illustrating a chuck fortools according to a seventh embodiment of the invention.

FIG. 16 is a left side view of the FIG. 15 embodiment.

FIG. 17 is a sectional view, taken on the line 17--17 of FIG. 15 andviewed in the direction of arrow, showing a buffer cylinder of the FIG.15 embodiment.

FIG. 18 is a enlarged view showing a portion surrounded by line 18 inFIG. 15.

FIG. 19 is a view showing the FIG. 18 portion placed in differentoperational condition.

FIG. 20 is a developed plan view showing part of the buffer cylinder ofthe FIG. 15 embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figures in the accompanying drawings following FIG. 2 inclusiveillustrate first seventh embodiments of the invention and in thesefigures, members used in common for these embodiments and similar tothose of the prior art example will be designated by the same referencenumerals as used in FIG. 1 and only the other different members will bedesignated by different reference numerals.

In the first embodiment as shown in FIGS. 2 and 3, a main body 1 has arear shaft 25, and a cylindrical first grip 17 has its flat bottomintegrally connected to the rear shaft 25 and its outer circumferentialperiphery formed with a great number of axial recesses 18.

An annular groove 9 is formed in the main body 1, and in forward part ofthe annular groove 9, there is disposed a rotary member 19 consisting ofa plurality of divided segments which are put together by means of ahoop 20 and in rearward part of the annular groove 9, there is disposedan annular seat 22. A number of bearing balls 21 are received in annulargrooves respectively formed in the two members 19 and 22. The inner wallof each segment of the rotary member 19 is thread with a female screw 8which meshes with a male screw 7 threaded on each jaw 2, and acylindrical second grip 23 is securely connected to the rotary member 19through the medium of the hoop 20. The second grip 23 has its rear endwhich is loosely fitted in a cavity of the first grip 17, providing fora gap between grips 17 and 23, and has its outer circumferentialperiphery formed with a number of axial grooves 24.

In this embodiment, when clamping or releasing a tool T, the first grip17 is gripped by one hand and the second grip 23 is gripped by the otherhand and thereafter the two grips 17 and 23 are relatively rotated inone direction or in the direction reverse thereto. Since the femalescrew 8 threaded on the rotary member 19 is in meshing engagement withthe male screws 7 on the jaws 2, this relative rotation causes the jaws2 to advance or retreat depending upon the direction of rotation of therotary member 19.

Thanks to the bearing balls 21 interposed between the rotary member 19and the seat 22 forming part of the main body 1, the rotary member 19can be rotated lightly.

FIGS. 4 to 7 show a second embodiment of the invention.

A first grip 27 in this embodiment differs from the corresponding gripof the first embodiment only in that an axial small hole 28 is boredthrough the flat bottom near its outer circumferential edge.

A main body 1 is recessed to form an annular groove 9 and provide anabutment 32 for supporting bearing balls 21 in the radial direction. Ahoop 20 is applied to a rotary member 29 as in the first embodiment butin the present embodiment, the rotary member 29 is not connected to asecond grip 33 through the medium of the hoop 20. The interconnectionbetween the two members 29 and 33 is accomplished by means of a couplingmember 30 in the form of an annular resilient member, as will bedescribed hereinafter. The second grip 33 has a rearward innercircumferential surface cooperative with the rotary member 29 to supportthe bearing balls 21, and in a cavity defined by the rearward innercircumferential surface, a cylindrical transmission member 34 is mountednot rotatably but axially movably with respect to the second grip 33,that is, in spline fashion, for example.

The coupling member 30 has a ring plate 35 and the ring plate 35 isdisposed between opposing circumferential surfaces of the two members 29and 33 as best seen in FIG. 5. Two tongues 36 integral with the ringplate 35 extend forwardly from the inner circumferential edge of thering plate 35 at about 180° spaced circumferential positions and thering plate 35 is recessed at diametrally opposite positions, 90° spacedapart from the tongues, to form two rearward projections 37. The tongues36 are snugly fitted in recesses 38 formed in the second grip 33 and therearward projections 37 are received in recesses 39 formed in the rotarymember 29 when the jaws 2 clamp a tool T, as best seen in FIGS. 4 and 7.The second grip 33 is formed with two sectoral recesses 40, each recess40 having the half which makes an angle of about 60° to the center lineof each recess 39.

In a cavity between the transmission member 34 and the first grip 27,there is disposed a pusher member 41 having a screw 43 in meshingengagement with a rearward shaft 42 of the main body 1. The direction ofthreading for the screw 43 is designed to be inverse to the direction ofthreading for the screws 7 and 8.

The pusher member 41 is formed with a small hole 44 which is axiallyaligned with the small hole 28 in the first grip 27, and the oppositeprojecting ends of a torsion spring 45 interposed between the first grip27 and pusher member 41 are snugly fitted in the small holes 28 and 44.

The tool T is clamped as shown in FIG. 4 in accordance with the presentinvention. In order to move the jaws 2 from their release position tothe illustrated clamping position, the grips 27 and 33 are relativelyrotated in one direction as in the case of the first embodiment.

During this operation, as the second grip 33 rotates, the couplingmember 30 having its tongues 36 snugly fitted in the recesses 38 in thesecond grip 33 is rotated to urge the projections 37 of the couplingmember 30 against the side wall of the recesses 39 so as to eventuallyrotate the rotary member 29, thereby causing the screws 7 and 8 inmeshing engagement with each other to advance the jaws 2 until theyengage the tool T at the position illustrated in FIG. 4. During thisadvance of the jaws 2, the pusher member 41 is in intimate contact withthe flat bottom of the first grip 27 by the action of the torsionsprings 45.

Subsequently, as the second grip 33 continues to further rotate in thesame direction, the jaws 2 push the rotary member 29 rearwardly and aresulting force is transmitted to the bearing balls 21 and transmissionmember 34 to mutually press the opposing surfaces of the transmissionmember 34 and pusher member 41, thereby ensuring that the pusher member41 can rotate together with the transmission member 34 in opposition tothe force of the torsion spring 45 under the influence of friction dueto the mutual pressing. This rotation of the pusher member 41 cooperateswith the action of the screw 43 to advance the pusher member 41 to theleft, before the projections 37 of the coupling member 30 climb over theside wall of the recesses 39 in the rotary member 29 (with the ringplate 35 deflected within the sectoral recesses 40) to release therotary member 29 from coupling with the second grip 33, thereby stoppingthe rotation of the rotary member 29. The advance motion of the pushermember 41 is transmitted to the rotary member 29 through the axiallymovable transmission member 34 and bearing balls 21, so that the rotarymember 29 and the jaws 2 coupled thereto through the screws 7 and 8 areadvanced from solid-line position to chained-like position in FIG. 6 tostrongly clamp the tool T.

When releasing the thus clamped tool T, the second grip 33 is rotated inthe other direction that is reverse to the previously-describeddirection. During this rotation, the rotary member 29 still remains tostop rotating but the action of the friction is mitigated, with theresult that the pusher member 41 is assisted by the recovery force ofthe spring 45 to rotate in the reverse direction so as to recover itsoriginal position, thus removing the forward pushing force exerted bythe pusher member 41 upon the rotary member 29. As the coupling member30 is further rotated, the projection 37 return to the recesses 39 inthe rotary member 29. With the projections 37 again received in therecesses 39, the rotation of the second grip 33 is transmitted to therotary member 29 to cooperate with the screws 7 and 8 in meshingengagement so as to retreat the jaws 2, thereby releasing the tool Tcompletely and returning all members to the state before clamping.

In the present embodiment, a spring for forwardly urging the grip 33 maybe inserted in a gap 66 between the outer circumferential periphery ofthe second grip 33 and the inner circumferential periphery of thecylindrical portion of first grip 27. Further, in order to increasefriction between the opposing surfaces of the transmission member 34 andpusher member 41, a face ratchet or a friction shoe, for example, may beinterposed between these surfaces.

FIGS. 8 to 10 show a third embodiment.

A first grip 17 in this embodiment is structurally identical to thecorresponding member of the first embodiment.

A second grip 50 in this embodiment is a cylindrical member made ofplastic and has a forward portion in which a rotary member 49 is fixedby press fitting. The rotary member 49 is formed with a radial throughhole 51, and bearing balls 21 are sequentially inserted through thethrough hole 51 and received in an annular groove 52 in a main body 1and an annular groove 53 in the rotary member 49. Each of the annulargrooves 52 and 53 has a cross-section defined by a radius which islarger than the radius of the bearing ball 21 (see FIG. 10). Denoted by54 is a plug block fitted in the through hole 51.

In accordance with the present embodiment, when clamping or releasing atool T, grips 17 and 50 gripped by hands are relatively rotated as inthe previous embodiments. During this operation, a reaction force due toclamping the tool T is applied to the rotary member 49 through jaws 2 ina direction of arrow in FIG. 10. This force causes the two members 1 and49 to apply a force to the bearing balls 21 on an inclined chained-lineP, indicating that radial and axial components of the force cansimultaneously be supported by the bearing balls 21 circumferentiallyarranged. Therefore, any separate bearings for supporting the twocomponents of the force can be dispensed with.

Fourth and fifth embodiments shown in FIGS. 11 and 12 are partialmodifications of the third embodiment. Specifically, in the fourthembodiment, a plug block 56 applied to a through hole 51 for insertionof bearing balls 21 is formed integrally with the inner surface of asecond grip 57, a hoop 58 for a rotary member 49, terminating in arearward end including a first portion bent inwardly at about rightangles and a second portion 59 contiguous to the inner end of the firstportion and bent forwardly at about right angles, the second portion 59being supported on a rearward shaft 25 of a main body 1.

In the fifth embodiment, hoop 61 substituting for the hoop 20 of thethird embodiment by having the same function is integrally formed withthe inner surface of a second grip 62.

FIG. 13 and 14 show a sixth embodiment.

In accordance with the sixth embodiment, a rotary member 65 is formed,at its forward surface, with a plurality of (three in the figures)sectoral recesses 66 and, at its rearward surface, with an annular step67. A second grip 68 is made of plastic and formed with sectoralprojections 69 which are fitted in the recesses 66. A hoop 70 fitted ina gap between the two members 65 and 68 by press fitting extendsrearwardly, terminating in a rear-ward end which is stopped by a chipring 71 mounted to the inner surface of the second grip 68. Bearingballs 21 are disposed in a cavity defined by the annular step 67, thehoop 70 and a support ring 72 provided on a portion, confronting theballs 21, of a main body 1.

A seventh embodiment as shown in FIGS. 15 to 20 is a partialmodification of the sixth embodiment and in the present embodiment, abuffer stop cylinder 75 is interrupted between first and second grips 17and 68.

The buffer stop cylinder 75 has a cylindrical main body 76 which has, atits forward outer circumferential edge, a flange 77 and, at its forwardinner circumferential edge, a plurality of (three in the illustration)projections 78 which are slidably inserted in recesses 24 formed in theouter periphery of the second grip 68. As best seen in FIGS. 17 and 20,the main body 76 is axially cut from the rearward end thereof to form aplurality of pairs (three pairs in the illustration) of radial cuttings79, thus providing a plurality of (three in the illustration) pawls 80at equal angular intervals. The rearward end of each resilient pawl 80is formed with an engaging recess 81. A cylinder wall portion 83intervening between adjacent resilient pawls 80 and integral with bufferstop cylinder 75 is formed, at its rearward end, with serrations 82.

An inner circumferential surface portion, facing the serrations 82, ofthe first grip 17 is formed with serrations 84 which are slidablyengageable with the serrations 82. An annular projection 85 extendingfrom the inner circumferential surface of the fast grip 17 is engageablewith the engaging recess 81.

In the fourth to seventh embodiments, clamping and releasing of the toolT can be effected through the same operation as in the case of the firstto third embodiments and will not be described herein.

In connection with the seventh embodiment, FIG. 18 particularlyillustrates the state before clamping. The clamping operation is startedfrom this state by relatively rotating the first and second grips 17 and68. During this operation, the buffer stop cylinder 75 is rotatedtogether with the second grip 68 since the projections 78 of the bufferstop cylinder 75 are in engagement with the recesses 24.

After completion of clamping, the buffer stop cylinder 75 is pushedrearward as shown at arrow in FIG. 18 so that the resilient pawls 80 arepushed down by the annular projection 85 so as to deflect downwards bytheir resiliency, thus permitting the projection 85 to engage therecesses 81 (FIG. 19) and the serrations 82 engaged the serrations 84 tosecurely couple the two grips 17 and 68 together (FIG. 19).

Consequently, a rotary member 65 and a main body 1 are securely coupledtogether to guard the rotary member 65 against becoming loose andagainst providing insufficient clamping even when the rotary member 65is vibrated during working operation performed using the chuck. Thisstate shown in FIG. 19 can be returned to the original state shown inFIG. 18 by withdrawing the buffer stop cylinder 75 in the direction ofarrow in FIG. 19.

Although particular preferred embodiments of the invention have beendisclosed in detail for illustrative purposes, it will be recognizedthat variations or modifications of the disclosed apparatus, includingthe rearrangement of parts, lie within the scope of the presentinvention.

What is claimed is:
 1. A chuck for tools comprising,a main body with anaxially extending hole through said main body defining a longitudinalaxis of the chuck, a plurality of oblique slots in the main bodyconverging on said longitudinal axis to act as guides for jaw members, aplurality of jaws slidably received in said oblique slots, each of saidjaws provided with an outer surface and a male thread portion, a rotarymember having a female thread portion in meshing engagement with each ofsaid male thread portions of said jaws and rotatably mounted on saidmain body, a first grip integrally connected to said main body, ballbearing mass interposed between said rotary member and said main bodyfor minimizing friction between the two, a second grip rotatably coupledto the rotary member for applying a rotative torque to the rotarymember, a buffer stop cylinder longitudinally movable relative to saidfirst and second grips between first and second position, releasablelocking means on the stop cylinder and said first and second grips forlocking the first and second grips together when said buffer stopcylinder is positioned in said first position and releasing the firstand second grips from each other when said buffer stop cylinder ispositioned in said second position.
 2. The chuck of claim 1 wherein thereleasable locking means includes,a resilient pawl on the stop cylinder,coacting projection and recess means between the pawl and one of thegrips for releasably connecting the pawl to the one grip, coactingserration means between said stop cylinder and said one grip forrotatably coupling the first and second grips together, and nonrotatableengaging means between the cylinder and the other of the grips.